Methods and apparatus for visual cues for eye alignment

Abstract

A retinal imaging device includes a camera, a light source, a projector, an I/O device and a computer. The projector emits two sets of light rays, such that one set of rays lies on an exterior surface of a first cone, and the other set of rays lie on an exterior surface of a second cone. The user adjusts the position of his or her eye relative to the camera, until the rays form a full, undistorted target image on the retina. This full, undistorted image is only seen when the pupil of the eye is positioned in the intersection of the first and second cones, and the eye is thus aligned with the camera. The user provides input, via the I/O device, that the user is seeing this image. The computer then instructs the camera to capture retinal images and the light source to simultaneously illuminate the retina.

What is claimed is: 
     
       1. An apparatus comprising:
 (a) a camera; 
 (b) a light source; 
 (c) a projector for emitting a first set of light rays and a second set of light rays, such that:
 (i) the first set of light rays lies on an exterior surface of a first cone, 
 (ii) the second set of light rays lie on an exterior surface of a second cone, 
 (iii) a first 3D region exists, which region is the intersection of the first and second cones, 
 (iv) when a pupil of an eye of a user is positioned in the region and the eye is looking at the camera, the first and second set of light rays form a first image on the retina of the eye, and 
 (v) when the pupil is not positioned in the region, the first and second set of light rays do not form the first image on the retina; 
 
 (d) an I/O device for receiving, from the user, input indicating that the user is seeing the first image; and 
 (e) one or more computers for outputting, based on the input, instructions
 (i) for the camera to capture one of more retinal images of the retina, and 
 (ii) for the light source to illuminate the retina while the camera captures the retinal images. 
 
 
     
     
       2. The apparatus of  claim 1 , wherein:
 (a) the projector is configured to emit light that has a first color; 
 (b) the light source that illuminates the retina is configured to emit light that has a second color; and 
 (c) the first and second colors are different from each other. 
 
     
     
       3. The apparatus of  claim 1 , wherein:
 (a) the apparatus further comprises
 (i) one or more sensors for gathering sensor data indicative of location of the eye, and 
 (ii) an electronic screen for displaying a visual display that is visible to the user; and 
 
 (b) the one or more computers are programmed
 (i) to calculate, based on the sensor data, one or more spatial coordinates of a point in the eye, and 
 (ii) to output, based on the one or more spatial coordinates, instructions to modify the visual display. 
 
 
     
     
       4. The apparatus of  claim 3 , wherein the visual display includes a symbol that indicates a direction of movement, which direction is towards the first 3D region. 
     
     
       5. The apparatus of  claim 1 , wherein the projector is configured to emit the first and second sets of light rays such that, when the eye is looking toward the camera and the pupil is in a second 3D region that does not overlap with the first 3D region, a second image forms on the retina, which second image is different than the first image. 
     
     
       6. The apparatus of  claim 5 , wherein the second image comprises a distorted version of the first image. 
     
     
       7. The apparatus of  claim 5 , wherein the second image comprises a truncated version of the first image. 
     
     
       8. The apparatus of  claim 1 , wherein, when the pupil is in the first 3D region and the eye is looking toward the camera and is focused at optical infinity, each light ray in the first and second sets of rays strikes the retina at a retinal location, which retinal location is different than any other location at which any other ray in the first and second sets strikes the retina. 
     
     
       9. The apparatus of  claim 8 , wherein, when the pupil is in the first 3D region and the eye is looking toward the camera and is focused at optical infinity, each light ray in the first and second sets of rays also strikes the pupil at a pupil location, which pupil location is different than any other location at which any other ray in the first and second sets strikes the pupil. 
     
     
       10. The apparatus of  claim 1 , wherein:
 (a) the first set of light rays converges to an apex of the first cone, at a first apex angle; 
 (b) the second set of light rays converges to an apex of the second cone, at a second apex angle; and 
 (c) the first and second apex angles are different from each other. 
 
     
     
       11. A method comprising, in combination:
 (a) a projector emitting a first set of light rays and a second set of light rays, such that
 (i) the first set of light rays lies on an exterior surface of a first cone, 
 (ii) the second set of light rays lie on an exterior surface of a second cone, 
 (iii) a first 3D region exists, which region is the intersection of the first and second cones, 
 (iv) when a pupil of an eye of a user is positioned in the region and the eye is looking at a camera, the first and second set of light rays form a first image on the retina of the eye, and 
 (v) when the pupil is not positioned in the region, the first and second set of light rays do not form the first image on the retina; 
 
 (b) an I/O device receiving, from the user, input indicating that the user is seeing the first image; and 
 (c) one or more computers outputting, based on the input, instructions
 (i) for the camera to capture one of more retinal images of the retina, and 
 (ii) for a light source to illuminate the retina while the camera captures the retinal images. 
 
 
     
     
       12. The method of  claim 11 , wherein:
 (a) the projector emits light that has a first color; 
 (b) the light source that illuminates the retina emits light that has a second color; and 
 (c) the first and second colors are different from each other. 
 
     
     
       13. The method of  claim 11 , wherein:
 (a) one or more sensors gather sensor data indicative of location of the eye; 
 (b) an electronic screen displays a visual display that is visible to the user; and 
 (c) the one or more computers
 (i) calculate, based on the sensor data, one or more spatial coordinates of a point in the eye, and 
 (ii) output, based on the one or more spatial coordinates, instructions to modify the visual display. 
 
 
     
     
       14. The method of  claim 13 , wherein the visual display includes a symbol that indicates a direction of movement, which direction is towards the first 3D region. 
     
     
       15. The method of  claim 11 , wherein:
 (a) a second 3D region exists, which does not overlap with the first 3D region; and 
 (b) when the pupil is located in a second 3D region and the eye is looking toward the camera, a second image forms on the retina, which second image is different than the first image. 
 
     
     
       16. The method of  claim 15 , wherein the second image comprises a distorted version of the first image. 
     
     
       17. The method of  claim 15 , wherein the second image comprises a truncated version of the first image. 
     
     
       18. The method of  claim 11 , wherein, when the pupil is in the first 3D region and the eye is looking toward the camera and is focused at optical infinity, each light ray in the first and second sets of rays strikes the retina at a retinal location, which retinal location is different than any other location at which any other ray in the first and second sets strikes the retina. 
     
     
       19. The method of  claim 18 , wherein, when the pupil is in the first 3D region and the eye is looking toward the camera and is focused at optical infinity, each light ray in the first and second sets of rays also strikes the pupil at a pupil location, which pupil location is different than any other location at which any other ray in the first and second sets strikes the pupil. 
     
     
       20. The method of  claim 11 , wherein:
 (a) the first set of light rays converges to an apex of the first cone, at a first apex angle; 
 (b) the second set of light rays converges to an apex of the second cone, at a second apex angle; and 
 (c) the first and second apex angles are different from each other.